Guillaume started at Caltech as a Dreyfus Foundation postdoctoral fellow in Environmental Chemistry in 2010. He worked with Jess Adkins and myself using mulitcollector ICP-MS to produce records of the isotopic composition of marine sulfate. In 2013 he transitioned to being the lab manager for the Adkin's lab, but continued his research on S isotope records by MC-ICPMS. He received his PhD from the Institute de Physique du Globe de Paris (France) working with Dr. Jérôme Gaillardet. Currently he's a researcher at the Centre de Recherches Pétrographiques et Géochimiques in Nancy, France.